age = int(input("请输入你家狗的年龄："))
if age <= 2:
    a = age * 10.5
    print(str(age) + "相当于人类年龄" + str(a))
else:
    a = 21 + (age - 2) * 4
    print(str(age) + "相当于人类年龄" + str(a))
